A Prospective Study of G-CSF Primed Bone Marrow from Pediatric Donors as a Stem Cell Source for Allogeneic Bone Marrow Transplant: A Pediatric Blood and Marrow Transplant Consortium (PBMTC) Study.

Higher bone marrow cell dose has been associated with improved survival after allogeneic BMT. Although PBSC provides higher cell dose, it also provides a higher number of T cells which increases the risk of GVHD and may negatively impact the outcome in pediatric patients. A prospective multi-center trial was conducted to evaluate the safety and feasibility of G-CSF primed bone marrow in children receiving HLA-identical sibling bone marrow transplantation (BMT). Thirty eight children at 9 different centers, 17 female and 21 male with a median age of 9.8 years (range 0.8–17) were enrolled between May 2003 and May 2005. Fifteen patients had high risk diseases (ALL ≥CR2=4, AML≥ CR2/refractory=5, Advanced MDS=3, JMML=1, NHL=2) and 23 had standard risk disease (SAA=6, Red Cell Aplasia=1, Sickle cell disease=1, CML-CP=2, AML CR1=9, ALL CR1=2, MDS-RA=2). Five patients had undergone a prior allogeneic transplant. All patients received myeloablative preparative regimens (Cy/TBI±VP-16=12, BU/Cy±other=20 and Cy/ATG=6) and 32 (84%) received CSP/FK506 with MTX as GVHD prophylaxis. Donors were HLA identical siblings except for one who was syngeneic. Donors with median age of 9.2 y (range 1.1–22) received 5 mcg/kg/day of GCSF SQ for 5 consecutive days. Bone marrow was collected on the fifth day with a median volume of 14.5 cc/kg (range 5.2–25). No donor experienced any complications related to G-CSF administration or harvest, up to the time of last follow-up at one month after the harvest. The absolute CD34 cell count at the day of the harvest was measured in 28 patients and it was significantly higher in bone marrow compared to peripheral blood, median of 50/μl (8–247) vs 513/μl (116–156) respectively (p <0.0001). Median nucleated and CD 34 cells infused was 8.4x10⁸/kg (range 2.4–60.9) and 8.7x10⁶/kg (range 2–27.6) respectively. No G-CSF was administered post transplant. All patients had neutrophil engraftment at a median of 19 days (13–28), and all but one patient with early post-transplant relapse had platelet engraftment at a median of 20 days (9–44). Thirteen patients (35%) developed grade 2 GVHD and 4 of 34 evaluable patients (12%) developed chronic GVHD (3 limited and 1 extensive). There was no transplant related mortality. Among 30 patients with malignant disorders 9 (30%) relapsed (6 with high risk and 3 with standard risk disease). The EFS and OS of patients with standard disease at 1 year is 84% (95% CI 68–100%) and 95% (95% CI 87–100) respectively. With a median follow up of 1 year the estimated EFS and OS of all patients at one year is 76% (CI 62–93) and 92% (95% CI 83–100) respectively. We conclude that G-CSF primed bone marrow from pediatric donors is safe and can result in high NC and CD34 cell dose that facilitate engraftment after myeloablative BMT without a discernable increase in the risk of GVHD. A prospective randomized trial comparing G-CSF primed bone marrow to unstimulated marrow is planned.